When manufacturing semiconductor devices, LCD (Liquid Crystal Device) substrates or the like, a predetermined pattern mask is formed on a semiconductor wafer (hereinafter, referred to “wafer”) by applying a resist liquid on the surface of the wafer, exposing the wafer and developing the wafer. It has been conventionally known that fine asperities are formed on the surface of a resist pattern after the development process, which may have an undesirable effect on a pattern line width when a subsequent etching process is performed. In order to resolve the above problem, a smoothing process has been proposed to improve a line edge roughness (LER) or a line width roughness (LWR) of the resist pattern.
This smoothing process is performed by forming an atmosphere of a solvent vapor to be used to dissolve the resist in a processing vessel, exposing the resist pattern to the atmosphere, and swelling a surface layer portion of the resist pattern. By performing the smoothing process, the surface layer portion is dissolved by the solvent and is smoothed. As a result, the surface roughness of the resist pattern is improved and the shape of the pattern is corrected.
In the above described smoothing process, however, other wafers that are in queue outside the processing vessel may be affected by proximity to the processing vessel. Thus, there is a need to fully exhaust the interior of the processing vessel and reduce a concentration of the remaining solvent to a predetermined reference value or less, in order to contain the effect on the other wafers, before a subsequent wafer to be processed is carried into the processing vessel after the processing vessel is opened and a processed wafer is carried out. However, such an exhaust process requires a considerable amount of time, which causes deterioration in throughput. The problem of throughput deterioration during the exhaust process has not been resolved in the conventional technique.